| Today, wireless sensor networks are widely used in life, science research and other fields. Richmultimedia information, such as sound, images, video, etc. are gradually introduced into wirelesssensor networks,this trend promotes the development of Wireless Multimedia Sensor Networkstechnology.This thesis firstly analyzes the current situation of wireless multimedia sensor networks andZigBee technology, secondly analyzes several common voice codec technology, lastly proposes aZigBee-based wireless voice communication system.This paper also gives the design of hardwarecircuit for this system. The system consists of ZigBee wireless transmission subsystem and voiceprocessing subsystem.The main control chip of ZigBee wireless transmission subsystem is CC2530and the platform of the software is TI’s ZigBee protocol stack ZStack-CC2530-2.3.0-1.4.0. Themain control chip of voice processing subsystem is TMS320VC5509A, voice codec standard isG.729A.Considering nodes may often move in a voice communication system, this thesis designed amethod to detect whether the router node leaves its parent communication range or not,and afterrejoin the network the node also send its network address to the original communications node, thismethod ensures the normal voice communication when the nodes move randomly. It is easier toarouse a broadcast storm when the nodes move in the network, so this thesis presents a improvedAODVjr routing algorithm based on the neighbor nodes, the simulation results show that thisimproved algorithm has less routing request packets and smaller loss rate than the originalalgorithm. Taking into account the quality of voice transmission, this thesis presents a bufferalgorithm based on packet sequence number, which can effectively eliminate the voice jitter.The overall system test result shows that the proposed ZigBee-based wireless voicecommunication system can achieve the basic voice communication features: single-hop broadcastcommunication and multi-hop unicast communication. |
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